Benzene in blood as a biomarker of low level occupational exposure

The occupational airborne exposure to benzene of 150 workers employed in pe trol stations and a refinery plant was assessed using personal sampling pum ps. Ail workers provided blood samples after the end of work and on the fol lowing morning before resuming work. Benzene concentrations in the blood of 243 non-occupationally-exposed subjects were also measured. The median occ upational benzene exposure for all 150 workers studied was 80 mu g/m(3). ov erall median brood benzene of ail workers was 251 ng/l at the end of the sh ift, and 174 ng/l the following morning. The benzene concentrations measure d in blood collected the following morning proved to be significantly lower than those measured at the end of the shift. Median blood benzene for the 243 'normal' subjects was 128 ng/l, which was significantly lower than that measured in the workers before a new work shift. The median blood benzene concentration was significantly higher in smokers than in non-smokers, both in the general population (210 ng/l vs. 110 ng/l) and in the exposed worke rs at the end of the shift (476 ng/l vs. 132 ng/l) and the following mornin g (360 ng/l vs. 99 ng/l). End-of-shift blood benzene correlated significant ly with environmental exposure; this correlation was better in the 83 non-s mokers than in the 67 smokers. In non-smokers with the median benzene occup ational exposure of 50 mu g/m(3), no difference was found in blood benzene concentration in exposed and non-exposed subjects. (C) 1999 Elsevier Scienc e B.V. All rights reserved.